The present invention proposes a scheme of efficiently relaying information to users of an overall system via cooperative delivery using a direct communication between terminals among the users. Before the present invention is explained, direct communication between terminals is explained. FIG. 1 is a conceptual diagram for the direct communication between terminals.
Referring to FIG. 1, a UE1 and a UE2 perform direct communication between terminals between the UE1 and the UE2 and a UE3 and a UE4 perform direct communication between terminals between the UE3 and the UE4 as well. An eNB can control a position of a time/frequency resource, transmit power and the like for performing direct communication between UEs via an appropriate control signal. Yet, if UEs are positioned at the outside of coverage of the eNB, direct communication between the UEs can be configured to be performed without the control signal of the eNB. In the following, direct communication between terminals is called D2D (device-to-device) communication.
Meanwhile, when a base station relays a given amount of information to all users in a system, a part of the users can receive a preferred amount of information in early stage with the help of a good channel state. In this case, having successfully received the information, the users can relay the information to users who have failed to successfully receive information due to relatively poor channel environment. In order to efficiently relay information, multi-users can relay the information in a manner of forming V-MIMO (virtual multiple input multiple output) via D2D communication, a base station transmits information to enable users of an overall system to efficiently receive the information in consideration of relay via D2D communication and the base station can divide the users into user groups appropriate for the D2D communication.